Chapter XV —185— Origin of Vacuoles 



as corresponding to specialized vacuoles, for the same reason that 

 we consider as specialized vacuoles, those encountered in the 

 phanerogams in which group of plants phenolic compounds are 

 always localized in vacuoles, often having forms corresponding to 

 those of the physodes. Chadefaud, who recently described simi- 

 lar physodes in the Phaeophyceae, thinks, on the contrary, that 

 these inclusions are chondriosomes which elaborate mucilages and 

 phenolic compounds. This opinion does not seem plausible to us. 



The same peculiarities are found in Vaucheria in which the re- 

 cent work of Mangenot has shown, apart from the central vacu- 

 olar canal previously discussed, the existence of numerous small, 

 peripheral rod- or granule-shaped vacuoles formed of a very con- 

 centrated colloidal substance. These small vacuoles which P. A. 

 Dangeard confused with the chondriosomes, take a blue color with 

 cresyl blue whereas the vacuolar canal stains violet. Mangenot 

 thinks these small vacuoles are composed of mucilages with which, 

 in a great many cases, tannins are associated. 



In Euglena viridis, as well as small vacuoles composed of a 

 concentrated solution of metachromatin, there are found in the 

 sub-cuticular cytoplasmic layer, spheres colored purple-violet by 

 cresyl blue and appearing as small vacuoles. According to Chade- 

 faud, these are specialized vacuoles containing mucus (Fr. corps 

 muciferes) . In this same region in other Euglenas, there are ob- 

 served elements shaped like bacteria, colored blue with cresyl blue, 

 rarely violet, which are capable of ejecting their contents as a long 

 filament. They seem to correspond to trichocysts such as are ob- 

 served in certain ciliates. 



In Cladophora (Fig. 103), P. A. Dangeard cited two categories 

 of vacuoles, those centrally placed which are large and liquid, others 

 at the periphery which are small, semi-fluid elements shaped like 

 rods. 



The existence of specialized vacuoles (with the exception of 

 those lacking in colloidal substances whose existence appears to be 

 connected with a phenomenon of syneresis), shows us that it is 

 not possible to consider the vacuome as a morphological entity in 

 the sense of Dangeard or to adhere to the theory of de Vries. 

 It is difficult, moreover, to keep for the term "vacuole" its classical 

 meaning and to limit it to liquid inclusions of the cell, since it is 

 now established that the well characterized vacuoles of the majority 

 of plants are themselves derived from semi-fluid inclusions whose 

 consistency is often greater than that of the cytoplasm itself, vacu- 

 oles which during the development of the cells again pass through 

 semi-fluid and even solid phases. Furthermore, we have seen that 

 in some lower plants the small inclusions, which, by the nature of 

 their contents and their predilection for vital stains, correspond un- 

 questionably to the vacuoles of more evolved plants, may remain 

 constantly in the semi-fluid state. 



One fact, however, stands out very clearly from the investiga- 

 tions just reviewed. It is that the protoplasm itself, i.e., living mat- 

 ter, is incapable of being stained with vital dyes except in a transi- 



